This section provides background information related to the present disclosure which is not necessarily prior art.
Automotive instrument clusters typically comprise large discreet display areas for a speedometer, a tachometer, and a number of smaller displays for coolant temperature, oil pressure, oil temperature, fuel level and the like. Arranged within and around the cluster are other indicators showing low fluid level conditions, turn signal operation, emergency light blinkers and so forth. In a conventional display, a rotating analog needle or pointer is provided for sweeping across a range of values to indicate a measured quantity. In other examples, a light beam can be used to scan across a similar range of values. Other configurations include digital displays that are operable to simply display a numerical value associated with a given unit of measurement.
In some instances, these instrument clusters may need to be reprogrammed, such as when a software update is needed. Generally, reprogramming can occur over the general controller area network (CAN) bus using an onboard module in the vehicle that acts as a diagnostic gateway. In many instances, a diagnostic connector in the foot well of the driver's side of the vehicle can be accessed by connecting a wired link from a handheld electronic device. This diagnostic connector provides a communication link that is generally optimized for response time and is not ideal for large file transfer speed. For example, in many instances, the top speed of the CAN by way of the wired diagnostic connector can be about 500 kilobytes per second. In real use, however, it is typical to only utilize 60% for data transfer, which leaves about 300 kilobits per second as a maximum data rate of transfer. This can be reduced further by the multiple connected modules.
Instrument clusters have been evolving recently to incorporate thin film transistor liquid crystal displays (TFT-LCD). The TFT-LCD's can be configured to display any information, such as information associated with any of the gauges and indicators listed above and/or information related to various components of the vehicle, such as the engine, transmission, fuel system and the like. As can be appreciated, the TFT-LCD's graphics can require an increased amount of stored data for operation. For example, some TFT-LCD displays can utilize between eight and sixteen megabytes of storage. With the conventional CAN bus update method utilizing the diagnostic connector described above, a reprogramming event can take over one hour per cluster.